CIRCUMFERENCE & AREA OF A CIRCLE

Front

What is the formula for the circumference of a circle?

Back

C = 2πr or C = πd, where r is the radius and d is the diameter.

Front

What is the formula for the area of a circle?

Back

A = πr², where r is the radius.

Front

If a circle has a radius of 10 m, what is its circumference?

Back

C = 2π(10) = 62.83 m.

Front

If a circle has a diameter of 20 m, what is its area?

Back

A = π(10)² = 314.16 m².

Front

What does the term 'diameter' refer to in a circle?

Back

The diameter is the distance across the circle through its center, equal to twice the radius.

Front

How do you convert diameter to radius?

Back

Radius = Diameter / 2.

Front

What is the circumference of a circle with a radius of 5 cm?

Back

C = 2π(5) = 31.42 cm.

Front

What is the area of a circle with a radius of 3 m?

Back

A = π(3)² = 28.27 m².

Front

If the circumference of a circle is 31.42 m, what is its radius?

Back

Radius = C / (2π) = 31.42 / (2π) = 5 m.

Front

What is the relationship between radius and diameter?

Back

The diameter is twice the radius (d = 2r).